Welcome to IBS!
I was on Zelnorm for many months and it did wonders for me. I'm female though, so I don't have a clue how it would affect your husband. BUT, since now it's approved for men I would definitely ask him to talk to his doc about
it. Sorry to say, I don't think there are any male IBSers on this board that have tried Zelnorm. I hope I'm wrong though and someone speaks up.
Good luck to you both!